高性能对称解耦结构的线振动陀螺

High performance single-crystal silicon symmetrical and decoupled vibrating gyroscope

为了最大限度克服微机电陀螺的两个模态的相互耦合作用,提高微机电陀螺的综合性能指标,采用国内现有MEMS标准工艺方法,设计和制作了一种高性能单晶硅对称解耦结构的线振动陀螺。采用对称结构形式和保证陀螺驱动和检测模态振型都是弯曲振动模式,易于模态匹配;由于采用驱动模态和检测模态结构解耦方式,从微结构设计上大大降低了正交耦合误差影响,使陀螺具有输出零位小、零偏稳定性好的优点。测试结果表明:初次加工的样机,在大气中驱动和检测模态固有频率分别在2430Hz和2580Hz左右,在150Hz带宽内具有0.1～0.5(°)/s的分辨率;随着加工精度的提高和检测电路的改进,该陀螺在大气中15Hz带宽内实现0.008(°)/s的分辨率,在真空状态下,这种高性能单晶硅对称解耦结构的线振动陀螺性能会有进一步的提高。

In order to decrease the orthogonal coupling error between the drive and sense vibration modes and improve the performance of the MEMS Gyro, according to the existing MEMS standard process in China, a single-crystal silicon symmetrical and decoupled （SYMDEC） gyroscope is designed and fabricated. The symmetric structure ensures the drive and sense vibration modes to be bending vibration mode and easily matched between them. Since the drive and sense modes adopt the decoupled structure, the orthogonal coupling error is significantly decreased from the design, and hence the gyro has the advantages of low output bias and the low bias drift, etc. Measurement results show that the resonant frequencies in drive and sense modes are about 2430 Hz and 2580 Hz respectively, and the sensor can sense angular rates as small as 0.5 deg/s even in atmospheric pressure. With the improvement in process precision and corresponding circuits, the gyroscope can provide a rate sensitivity of 0.008 deg/s within 15 Hz bandwidth at atmospheric pressure, and the performance maybe improve further at vacuum operation with matched modes.